If you want to catch a glimpse of Paris without doing the whole hop-on hop-off tourist bus thing, take the line 6 metro. It starts at Charles de Gaulle/Etoile (the Arc de Triomphe) and ends on the other side of Paris, at Nation. Most of the train ride is above ground, and you'll go by the Eiffel Tower, over the Seine, and through several different residential neighborhoods.

